1. Field of the Invention
The present invention relates to a semiconductor device.
2. Background Art
As disclosed in Japanese Patent Laid-Open No. 10-303198, for example, a semiconductor device in which a Via Hole penetrating a semiconductor substrate from a back surface side and reaching an electrode pad on a front surface is provided, and a solder is provided in this Via Hole has been known. In the semiconductor device according to this gazette, an electrode of a semiconductor element is provided on the front surface of the semiconductor substrate, and an opening reaching a lower surface of the electrode is provided on the back surface of the semiconductor substrate. After an Au film and a Ni film are sequentially laminated in this opening, the semiconductor substrate and a package substrate are bonded by using an AuSn solder.
Other prior art includes Japanese Patent Laid-Open No. 7-066384 and Japanese Patent Laid-Open No. 2007-095853.
Nickel has a property of repelling a solder. Thus, there is a concern that a region in which air remains in the solder is generated due to deterioration of close contact between the Ni film and the solder in the semiconductor device according to the above prior-art technology. This region in which air remains in the solder is also referred to as a void.
The solder in the Via Hole also has a role of diffusing heat generated when the semiconductor element is operating. If there is a void in the solder, such diffusion of heat is prevented. As a result, radiation through the solder is not performed, heat is accumulated in the semiconductor element, and characteristics of the semiconductor element deteriorate.